callable_method_pointer.h
callable_mp.h
This allows removing it from `class_db.h`, significantly reducing the amount of files that include it transitively. Also includes some include cleanup in `control.h` and `rich_text_label.h` done while ensure they don't depend on `callable_mp`.
Notably decouples it from: - AccessibilityServer - DisplayServer - Viewport - Window
class_db.h
Splits monolithic physics class files.